2015-03-31T18:22:27ZEfficient motion planning for high DOF hands using principal motion directionshttp://hdl.handle.net/2117/3071
Title: Efficient motion planning for high DOF hands using principal motion directions
Authors: Rosell Gratacòs, Jan; Suárez Feijóo, Raúl; Rosales Gallegos, Carlos; García, J.A.; Pérez Ruiz, Alexander
Abstract: The paper deals with the problem of motion planning of anthropomorphical mechanical hands avoiding collisions. The proposed approach tries to mimic the real human hand workspace, but reducing the dimension of the search space in order to obtain results as a compromise between motion optimality and planning complexity (time) by means of the concept of principal motion directions. Basically, the work includes the following phases: capturing the human hand workspace using a sensorized glove and mapping it to the mechanical hand workspace, reducing the space dimension by looking for the most relevant principal motion directions, and planning the hand movements using a sampling-based roadmap planner. The approach has been implemented for a four finger anthropomorphical mechanical hand, and some examples are included to illustrate its validity.2009-10-20T16:37:10ZModelo de planificación agregada de la producción, la plantilla, el tiempo de trabajo y la tesoreríahttp://hdl.handle.net/2117/3070
Title: Modelo de planificación agregada de la producción, la plantilla, el tiempo de trabajo y la tesorería
Authors: Boiteux, Orlando Dante; Corominas Subias, Albert; Lusa García, Amaia
Abstract: En este trabajo se propone un modelo de planificación agregada que incorpora, junto a la planificación de la producción, la gestión de la tesorería y las finanzas, a corto plazo, y la organización flexible del tiempo de trabajo, con un sistema de cuentas de horas.
Esto último, unido al hecho de considerar una relación no lineal entre la dimensión de la plantilla y la capacidad de la planta por unidad de tiempo, implica una relación entre producción y horas de trabajo disponibles más compleja y realista que la asumida en los modelos tradicionales de planificación agregada. En un previo análisis de la literatura (Boiteux et al., 2007a y 2007b) se detectan limitaciones de los modelos propuestos y la consiguiente necesidad de abrir nuevas líneas de investigación para que la planificación agregada pueda ser realmente un instrumento para determinar, a medio plazo, las actividades de las principales áreas funcionales de la empresa y para garantizar la coordinación de las mismas, mejorando de esta forma la eficiencia y los beneficios globales. El modelo de planificación agregada aquí propuesto pretende ser un paso en esta dirección.2009-10-20T16:20:54ZFinding a fourth contact that allows the loss of two out of three existing ones remaining as force-closure grasphttp://hdl.handle.net/2117/3069
Title: Finding a fourth contact that allows the loss of two out of three existing ones remaining as force-closure grasp
Authors: Prado, Ricardo; Suárez Feijóo, Raúl2009-10-20T14:55:50ZCapacidades de fabricación y almacenaje óptimas en un sistema con logística inversa y demanda aleatoriahttp://hdl.handle.net/2117/3067
Title: Capacidades de fabricación y almacenaje óptimas en un sistema con logística inversa y demanda aleatoria
Authors: Benedito Benet, Ernest; Corominas Subias, Albert
Abstract: En el presente trabajo se estudia un sistema con demanda y retornos aleatorios para calcular las capacidades óptimas de fabricación y almacenaje. El modelo presentado permite estudiar el comportamiento de las capacidades de fabricación y almacenaje óptimas cuando varían los costes de producción.2009-10-20T13:05:53ZNon-uniform sampling in digital repetitive control systems: An LMI stability analysishttp://hdl.handle.net/2117/2651
Title: Non-uniform sampling in digital repetitive control systems: An LMI stability analysis
Authors: Ramos Fuentes, Germán Andrés; Olm Miras, Josep Maria; Costa Castelló, Ramon
Abstract: Digital repetitive control is a technique which allows to track periodic references and/or reject periodic disturbances. Repetitive controllers are usually designed assuming a fixed frequency for the signals to be tracked/rejected, its main drawback being a dramatic performance decay when this frequency varies. A usual approach to overcome the problem consists of an adaptive change of the sampling time according to the reference/disturbance period variation. This report presents a stability analysis of a digital repetitive controller working under time-varying sampling period by means of an LMI gridding approach. Theoretical developments are illustrated with experimental results.2009-03-12T09:50:11ZRobust Exact Differentiation via Sliding Mode Technique applied to a Fixed-Frequency Quasi-Sliding Control Algorithmhttp://hdl.handle.net/2117/2360
Title: Robust Exact Differentiation via Sliding Mode Technique applied to a Fixed-Frequency Quasi-Sliding Control Algorithm
Authors: Biel Solé, Domingo; Fossas Colet, Enric; Meza Benavides, Carlos; Muñoz Aguilar, Raúl Santiago
Abstract: This paper presents the design of a DC-AC power converter controller that bears the same benefits of a sliding mode controller but with the advantage of a fixed-frequency control signal. The controller is based on the imposition of zero averaged value of the sliding surface in each switching cycle. A keypoint of the presented controller is the calculation of the sliding surface’s derivative which in the present paper is obtained using an estimation algorithm introduced by Levant in 1998.2008-11-13T15:10:55ZTaking decisions on assignment of tasks with path dependent learning curveshttp://hdl.handle.net/2117/2356
Title: Taking decisions on assignment of tasks with path dependent learning curves
Authors: Corominas Subias, Albert; Olivella Nadal, Jordi; Pastor Moreno, Rafael
Abstract: Performance in doing a task in the learning stage depends on the previous practice on other tasks –learning curve is path dependent. A mathematical program aimed to assign a set of tasks to a set of workers considering path dependent learning curves is presented. Due dates for task and final knowledge objectives are possible, some tasks can be subcontracted and temporary workers can be hired. The model allows obtaining the cost of due dates and final knowledge.2008-11-12T12:10:12ZTécnicas y algoritmos para la adquisición, transmisión y visualización de escenas 3Dhttp://hdl.handle.net/2117/2259
Title: Técnicas y algoritmos para la adquisición, transmisión y visualización de escenas 3D
Authors: Beltrán Guerrero, Diana; Basañez Villaluenga, Luis2008-09-29T10:31:48ZProgramming assignments to learn how to build a Probabilistic Roadmap Plannerhttp://hdl.handle.net/2117/2257
Title: Programming assignments to learn how to build a Probabilistic Roadmap Planner
Authors: Rosell Gratacòs, Jan; Pérez, Alexander
Abstract: Research in robot motion planning requires the availability of a simulation environment where to test and validate the theoretic contributions. Nevertheless, PhD programs and graduate studies that include robot motion planning courses usually cover the subject only from a theoretical perspective. Therefore, students aiming to focus their research in this line, face the big challenge of developing their own simulation environment. To cope with this problem, this paper proposes the use of a programming framework based on multi-platform open source code, and presents a set of twelve programming assignments to allow students of any robot motion planning course a quick mastering of the basic skills involved, covering from graphical rendering issues to collision detection or graph representations and algorithms.2008-09-22T14:42:01ZSampling C-obstacles border using a filtered deterministic sequencehttp://hdl.handle.net/2117/2256
Title: Sampling C-obstacles border using a filtered deterministic sequence
Authors: Rosell Gratacòs, Jan; Pérez, Alexander
Abstract: This paper is focused on the sampling process for path planners based on probabilistic roadmaps. The paper first analyzes three sampling sources: the random sequence and two deterministic sequences, Halton and sd(k), and compares them in terms of dispersion, computational efficiency (including the finding of nearest neighbors), and sampling probabilities. Then, based on this analysis and on the recognized success of the Gaussian sampling strategy, the paper proposes a new efficient sampling strategy based on deterministic sampling that also samples more densely near the C-obstacles. The proposal is evaluated and compared with the original Gaussian strategy in both 2D and 3D configuration spaces, giving promising results.2008-09-22T14:31:34ZExploration of the grasp space using independent contact and non-graspable regionshttp://hdl.handle.net/2117/2255
Title: Exploration of the grasp space using independent contact and non-graspable regions
Authors: Roa Garzón, Máximo; Suárez Feijóo, Raúl; Rosell Gratacòs, Jan
Abstract: This report presents the use of independent contact and non-graspable regions to generate the grasp space for 2D and 3D discrete objects. The grasp space is constructed via a sampling method, which provides samples of force-closure or non force-closure grasps, used to compute regions of the graspable or non-graspable space, respectively.
The method provides a reliable procedure for an efficient generation of the whole grasp space for n-finger grasps on discrete objects; two examples on 2D objects are provided to illustrate its performance. The approach has several applications in manipulation and regrasping of objects, as it provides a large number of force-closure and non force-closure grasps in a short time.2008-09-22T14:23:27ZDeterminación de las capacidades de fabricación y almacenaje óptimas en un sistema con logística inversa y demanda periódicahttp://hdl.handle.net/2117/2246
Title: Determinación de las capacidades de fabricación y almacenaje óptimas en un sistema con logística inversa y demanda periódica
Authors: Benedito Benet, Ernest; Corominas Subias, Albert
Abstract: En este trabajo se describe un método para calcular la capacidad de fabricación y de almacenaje en un sistema con logística inversa en el que la demanda es determinista y los retornos dependen de la demanda. Utilizando el método descrito, se muestra un ejemplo de la influencia que tiene la función de los retornos en las capacidades de fabricación y almacenaje.
El resto del trabajo se compone de cinco secciones más. En la segunda sección se describe el sistema que se va a estudiar. En la tercera, se proporciona un método para calcular la política de fabricación óptima, considerando fijadas las capacidades de fabricación y almacenaje. En la cuarta, se calculan las capacidades de fabricación y almacén óptimas utilizando el método descrito en la sección anterior. En la quinta, se aplica el método explicado en las secciones anteriores para estudiar la influencia del desfase de los retornos en las capacidades óptimas de fabricación y almacenaje. Finalmente se exponen las principales conclusiones del trabajo.2008-09-18T10:56:27ZSolving the Response Time Variability Problem by means of the electromagnetism-like mechanismhttp://hdl.handle.net/2117/2013
Title: Solving the Response Time Variability Problem by means of the electromagnetism-like mechanism
Authors: García Villoria, Alberto; Pastor Moreno, Rafael
Abstract: The Response Time Variability Problem (RTVP) is an NP-hard combinatorial scheduling problem that has recently appeared in the literature. The RTVP has a wide range of real-life applications such as in the automobile industry, when models to be produced on a mixed-model assembly line have to be sequenced. The RTVP occurs whenever products, clients or jobs need to be sequenced so as to minimize variability in the time between the instants at which they receive the necessary resources. The field of Artificial Intelligence has provided us with efficient tools such as metaheuristic techniques for solving complex combinatorial scheduling problems. In a previous study, three metaheuristic algorithms (a multi-start, a GRASP and a PSO algorithm) were proposed to solve the RTVP. These three metaheuristic algorithms have been most efficient, until now, in solving non-small instances of the RTVP. We propose solving the RTVP by means of the electromagnetism-like mechanism (EM) metaheuristic algorithm. The EM algorithm is based on an analogy with the attraction-repulsion mechanism of the electromagnetism theory, where solutions are moved according to their associated charges. In this paper we compare the proposed EM metaheuristic procedure with the three metaheuristic algorithms previously mentioned and show that, on average, the EM procedure improves on the obtained results.2008-05-16T07:47:35ZSolving the Response Time Variability Problem by means of a psychoclonal approachhttp://hdl.handle.net/2117/2007
Title: Solving the Response Time Variability Problem by means of a psychoclonal approach
Authors: García Villoria, Alberto; Pastor Moreno, Rafael
Abstract: The Response Time Variability Problem (RTVP) is a combinatorial scheduling problem which has recently appeared in the literature. This problem has a wide range of reallife applications in, for example, manufacturing, hard real-time systems, operating systems and network environment. Originally, the RTVP occurs whenever products, clients or jobs need to be sequenced in such a way that the variability in the time between the instants at which they receive the necessary resources is minimized. Since RTVP is hard to solve, heuristic techniques are needed for solving it. In a previous study, three metaheuristic algorithms (a multi-start, a GRASP and a PSO algorithm) were proposed to solve the RTVP. These three metaheuristic algorithms have been the most efficient to date in solving non-small instances of the RTVP. We propose solving the RTVP by means of a psychoclonal algorithm based approach. The psychoclonal algorithm inherits its attributes from the need hierarchy theory proposed by Maslow and the artificial immune system (AIS) approach, specifically the clonal selection principle. In this paper we compare the proposed psychoclonal algorithm with the other three metaheuristic algorithms previously mentioned and show that, on average, the psychoclonal algorithm strongly improves the obtained results.2008-05-14T09:07:17ZHeuristic procedures for solving the General Assembly Line Balancing Problem with Setups (GALBPS)http://hdl.handle.net/2117/1555
Title: Heuristic procedures for solving the General Assembly Line Balancing Problem with Setups (GALBPS)
Authors: Martino, Luigi; Pastor Moreno, Rafael
Abstract: The General Assembly Line Balancing Problem with Setups (GALBPS) was recently defined in the literature. It adds sequence-dependent setup time considerations to the classical Simple Assembly Line Balancing Problem (SALBP) as follows: whenever a task is assigned next to another at the same workstation, a setup time must be added to compute the global workstation time, thereby providing the task sequence inside each workstation. This paper proposes over 50 priority-rule-based heuristic procedures to solve GALBPS, many of which are an improvement upon heuristic procedures published to date.2008-02-01T09:52:02Z